Refrigeration



Aug. 22, 1944. w. L. MOGRATH REFRIGERATION Original Filed June 25, 1938 INVENTOR. William 1|. ME C11*;1314

ATTORNEY."

Patented Aug. 22,1944

NITED STATES PATENT OFFICE REFRIGERATION j William L. McGrath, Philadelphia, Pa., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Original application June 25, 1938, Serial. No.

215,796. Divided and this 1942, Serial No. 436,064

6 Claims.

The present invention relates to refrigerating systems employing condensers and the invention has-toido particularly with control of-the cooling of the condenser.

.The primary object of the invention is 'to pro-- denser, which diflerential may becompensated' in response to the'load on the system as measured by compressor discharge pressure.

This application is a division of my previously filed application, Serial No. 215,796 filed June 25, 1938, now Patent No. 20, 1942.

Further objects and advantagesofmy invention will become apparent from the following detailed description and annexed drawing,

' wherein Figure 1 is a diagrammatic representation of a refrigeration system embodying one form of my invention;

Figure 2 is a diagrammatic representation of a second form of my invention, and

Figure 3. is a third modified form of the invention.

a compressor l driven by a motor ll, the outlet of the compressor being connected by a pipe l2 to the condenser coil II, the outlet of the condenser being connected to a receiver I 4, there 2,299,335, issued October being a thermostatic expansion valve 15 for controlling the flow of refrigerant from the receiver l4 to an evaporator I6. Refrigerant flows from the evaporator I6 through a pipe IT to the inlet of the compressor I0. The operation of such a system will, be apparent to those skilled in the art. Lines 2| and 22, which may be connected to a suitable source of power not shown, are provided for supplying power to the motor I I. For controlling the-operation of the compressor a suction-pressure controller 23 may be provided, this controller including a bellows 24 connected by means of a pipe 25 to the compressor suction let of the compressor.

application March 25,

pipe. A lever 26 is biased by means of a spring ,head pressure controller 3| may also be pro-- vided for controlling the operation of the com pressor. This controller may include a bellows 32 connected by means of a pipe to they outat 36 and carrying a mercury switch 31 at one end thereof. The circuit through the motor II is as follows: from the line 2| through wire 40,

operate as long as the suction pressure is above a predetermined value and the discharge pressure is below a predetermined value. Should the suction pressure drop to a low enough value, the

switch 28 will be tilted in the opposite direction from that illustrated and interrupt the circuit to the motor' ll. Should the discharge pressure reach a predetermined high value the switch 31 will be tiltedby the bellows 32 in the opposite direction from that illustrated, and break the circuit to the motor ll. I

For cooling the condenser 13 water may be supplied to a tank- 45' housing the coil l3 by means of a pipe 46. controlled by a valve 41. The water may leave the tank 45 by means of a pipe 48. A motor 49 of the type shown in the patent of D. G. Taylor, No. 2,028,110 is connected by means ofa pinion 50 to a rack 51 connected to the valve stem 53 whereby the positionlof the valve is controlled in accordance with theoperation of the'motor 49. The motor 49 is controlled by a difierential pressure controller iii-which includes a bellows 59 and a. bellows 60 connected by means of capillary tubes 6| and 62 to bulbs 63, and 64 respectively mounted in intimate contact with the inlet pipe 46 and outlet pipe 48- resistance 69 by means of another lever 10 which n is normally biasedin a counterclockwise direc tion by a coil spring-Tl. Upon an increase in temperature difierential, the temperature at 48 of course being higher than that at 46, the arm 68 is moved to the right and upon a decreasein;

An arm 34 is biased b means of an adjustable spring 35 into engage-' ment with the bollows 3|, this arm being pivoted I let pipe 48 so that right end of resistance 89. As the temperature differential at 48 and 48 increases the arm 88 is moved towards "the right, thus decreasing the resistance between the terminals 14 and 15 and causing the motor to move the valve towards open position an amount which is proportional to the increase in temperature differential.

The arm 34 carries a control arm 85 suitably insulated therefrom and forming the slider of a compensating potentiometer having a resistance 86. The arm 85 is connected by means of wire 81, resistance 88, wire 89, and wire 18 to the motor terminal 14. The right end of resistance 88 is connected by means of wires 98' and 18, to the motor terminal 13 and the opposite end of this resistance is connected by means of wires 9! and 8| to the terminal 15 of'the motor 49. As. the

- pressure on the discharge side of the compressor l8 increases the bellows 32 will expand and cause the control arm 85 to move to the left over resistance 88, which will decrease the resistance connected between the terminals 14 and 15 whereby the valve 41 will be movedtowards open position. By reason of the resistance 88 connected in the circuit in the arm 85, this arm will have less effect on the motor than the arm 88 and will have the effect of shifting the control range of the arm 88 as the discharge pressure of the compressor l varies.

It will accordingly be seen that with the system shown in this figure, for given discharge pressure on the compressor the temperature differential between the inlet 48 and the outlet 48 for the condenser coolingwater will be effectively controlled by controllin the amount of water supplied to, 'the condenser whereby wasting of cooling water is eliminated. As the discharge pressure on the compressor increases a need for further cooling of the condenser is indicated and the control arm 85 is shifted towards the left,

thus shifting the control range of the arm '88 to the left to maintain a lower differential in temperature between the inlet pipe 48 and the outthe increased cooling of the condenser which is required will be effected.

Referring now to Figure 2, a refrigeration syscapillary tube 208 to a bulb 238 mounted in intimate contact with the inlet pipe 43, acts directly upon one side of the lever 28!. A second bellows 210 is connected by means of a capillary tube 2| l g to a bulb 2l2 mounted in intimate contact with the outlet pipe 48 and it acts against the opposite side of the lever 20! in opposition to the bellows 284. It will be understood that both of these assemblies of bellows elements, 'tubes and bulbs will be filled with'a suitable volatile fluid and it will be seen that the position of lever 2M will depend upon the relative pressures existing within the bellows elements 204 and 210 and therefore, upon the temperature differential between the inlet plpe:48 and the outlet pipe 48. As the temperature differential increases, the bellows 2"! will exert an increasingly greater net force on the lever 2M and cause clockwise movement thereof and consequent opening of the valve 41 whereby an increased supply of water is permitted by the valve 41 to decrease the temperature differential at 48 and 48. Also acting on the lever 2M in opposition of the bellows 204 is a bellows 215 connected by means of a pipe 2i8 to the discharge side of the compressor l0. As the discharge pressure increases, the bellows 2 I 8 will expand and for a given temperature differential at the inlet 48 and the outlet 4.8 an increase in the discharge pressure on the compressor will have the effect of moving the lever 2M in a clockwise direction; thus further opening the valve 41.

It will be apparent that with this system, the

valve 41 is operated in accordance with the differential in temperatures at the inlet 48 and the I Figure 3 shows another form of self contained unit wherein the operating mechanism may be built right into the valve mechanism. The water inlet pipe to the condenser is lllus trated at 48 and controlled by the valve 41. The.

valve stem 83 is connected to the upper wall of a small bellows 328,'this valve being biased to- .wards closed position by means of the spring 321. A cap-322 is suitably secured to the upper portion of the valve casing and forms an enclosed chamber whichmay be provided with a tem generally similar to that of Figure l is illustrated, this system including the compressor l0, condenser'l3, receiver l4, expansion valve l5, and evaporator 18. The'circuit for controlling the operation of the compressor is shown as being identical to that of Figure 1 and further description' thereof is unnecessary. It should be understood, however, that the control circuit for the compressor motor of Figures 1 and 2 may be modified in any of. the ways well known in the art.

The control means for the valve ,41 is shown to comprise a direct operating differential pressure controller 288 inplac'e of the motor 48 controlled by the diiferential pressure controller 88 andthe compensator 3| of Figure l. The valve,

stem 53 of the valve 41 is connected to. 'a lever 20! pivoted at 202 and biased by means of an adjustable spring 203 in a counter-clockwise direction. A bellows 284 connected by means of a suitable volatile fill. The temperature of the water flowing past the valve 41 will be communicated to the volatile fill enclosed by cap 322 by the wall 330. Depending from the upper wall of the casing 322 is a small bellows 324 whose lower end is connected to the valve stem 83, the upper end of this bellows being sealed to the upper wall of the casing 322. A pipe 328 may connect this small bellows to the high pressure side of the compressor. Also sealed to thet'opof thecasing 322 is a large bellows 323 whichmay be concentric withthe bellows 324 and also suitably connected at its lower end to the valve stem 283., A capillary tube 321 may connect this large bellows to a bulb mounted on the discharge side of the condenser, this large bellows,

girlie, and bulb-being filled with a suitable volatile The bellows 323 will be expanded upon an increase in temp rature at the discharge side of the condenser by reason of an increase in pressure of the volatile fillthereln and will be concondenser;

within said chamber and tracted by reason of'an increase in pressure of the volatile fill surrounding this bellows upon an increase in temperature at the inlet side of the This 'bellows will accordingly cause the valve 41 to assume positions depending upon the differential intemperature at the inlet and the outlet side of the condenser to increase the supply of water when the differentialincreases to reduce the supply of water as the differential decreases. As the pressure on the high pressure side of the compressor increases, the force exerted byrthe bellows 324 will increase and its eflect is added to the effect of the bellows 32S whereupon a lowepdifierential in temperature will cause an equal opening of the valve. In" other words-to open the valve a given amount it will take a smaller differential in tempera-. ture ii the discharge pressure of the compressor is higher than is required when the discharge pressure is low.

Having described the preferred forms of my invention many modifications and many adaptations may become apparent to those skilled in the art and it should be understood that my invention is limited only by the scope of-the appended claims.

I claim as my invention:

3. In a refrigeration system including a compressor, a condenser and an evaporator, meansfor circulating a cooling medium through the condenser, means in control of the flow of cooling sive to the pressure on the high pressure side of the compressor for also controlling the fiow controlling means.

4. In a system of the class described, a cooling unit, a valve for controlling thefiow of a cooling medium through said unit, said valve including a fiow-control member movable between positions of minimum and maximum flow, a pressure responsive device filled with an expansible fluid and responsive to the temperature of the cooling medium entering the cooling. unit acting on said movable member to. move said member to minimum flow position, a second pressure re- 1. In a' refrigeration system including a compressor, a condenser, and an evaporator,-.- means for-circulating a cooling medium through said condenser, a valve in control of the flow ofcooling medium through said condenser, an electric motor controlling the position of said valve, circuit controlling means controlling the. operation of said motor, means responsive to the temperature diflerential at the inlet andoutletof said condenser in control of said circuit controlling means, and means responsive to the pressure on the high pressure side of the compressor for varying the effect ofsaid circuit controllingf 'means on the motor insuch manner thata lower differential in temperature at the inlet and'outlet of the. condenser is maintained as the pressure on the high pressure side of the compressor increases.

2. In a system of the class described, a cooling unit, a valve for controlling the flow of a sponsive device filled. with an expansible fluid and responsive to the temperature of the cooling medium leaving the unit acting on said movable member to movesaid member to a maximum flow position, and a third pressure responsive device responsive to a condition indicative of a need for increased cooling by the cooling unit acting on said movable member to move said member toward maximum flow position as the need for further cooling by creases.

5. A control mechanism for a refrigeration system that includes a compressor for furnishing refrigerant to the systemunder high pressure and a condenser for the refrigerant cooled by the flow of a cooling fluid, comprising, in combination, a

the cooling unit incontrol valvefor controlling the flow of cooling fluid,said valve including a means movable between positions of minimum and maximum flow, a temperature-responsive device adapted to respond to the temperature of the fluid entering a said condenser for moving said movable means towards minimum-flow position upon rise in such temperature, a second temperature responsive device, adapted to respond to the temperature of cooling medium through said cooling unit, said valve comprisinga valve chamber having a valve seat and a valve member cooperating therewith, said valve member having a .valve stem extending outwardly from said chamber, means bias-- ing said valve towards closed position, a movable sealing member on the outside of said chamher and sealing the interior of said valve chamher from the space surrounding said valve stem, means forming a second chamber on' the outside of 'said valve chamber and around-said valve stem, said chamber being filled with a volatile fluid and subject to changes in temperature of the cooling medium passing through said valve, an expansible member within said second chamber and filled with a volatile fluidsublect to the temperature of th cooling medium leaving the cooling unit, and a second v filled with a volatile fluid, said fluid being subject to a condition indicative of a need for variations in the cooling eflect of the cooling unit, 1 said cxpansible members actingonthevalvestcmto open said valve inrolponss to mansion of said members.

expansible member the fluid leaving said condenser for moving said movable means towards maximum flow position uponrise in the temperatureof the fluid leaving ,the' condenser, and pressurev responsive means adapted to respond to the pressure oi' the refrigerant flowing to said condenser for moving said movable means towards maximum flow position upon increase in such pressure.

said system, in combination. means circulating a cooling fluid through said condenser for condens- -ing said refrigerant, means controlling the rate of circulation'of 'said'fluid in response to the temperature change of. said fluid as it passes through said condenser in such manner that the vrate of flow is increased as said diflerence tends to increase, and means responsiveto the demand for cooling of the refrigerant in said condenser modifying thecontrol exercisedv by said means controlling sai rate of flow in such manner as to increase said rate of flow as said demand increases wnmunmoas'in.

6. In' a refrigerating system including a refrigerant condenser in the high pressure sideof 

